OTHER TECH

Tech Notes DVDs and other video sources looked great on the computer monitor, using a VGA connection. DVD progressive-scan conversion was very good, and resolution was fine. When I connected the composite- and S-video outputs to a video monitor to watch a DVD movie, though, the picture's geometry and resolution were worse than the most inferior DVD player we've tested. If you use the coaxial digital audio output from the sound card to feed Dolby Digital and DTS signals from DVDs to an external decoder, as in an A/V receiver, you'll be okay. But if you use the computer's internal Dolby Digital decoder, you'll end up with multichannel analog outputs that go into limiting over the top 6 to 10 dB of dynamic range, regardless of how you set the numerous volume and sound-mixer controls. CD playback over the digital output, even with the default sampling rate set for the CD-standard 44.1 kHz, was not bit-perfect. Unlike Dolby Digital bitstreams, digital signals from CDs are volume controlled, and that processing seems limited to 16 bits of resolution. As a result, the noise floor of so-called "20-bit" CDs was raised to normal 16-bit levels. Despite this, the digital output from CDs was rather clean, with a -73.5-dB noise level (measured with the volume full up). While the bass-management system has a nifty crossover-frequency adjustment, when I set it for 82 Hz, I got a 100-Hz high-pass-filter crossover point for the main speakers and a 43-Hz point for the subwoofer output - a gap of more than an octave. Other frequency settings produced similar gaps. If multimedia computers are ever to replace the multiple components of a home theater system - as I believe they will some day - they're going to have to do better than this. - David Ranada